Method and apparatus for blow molding axially deformable containers

ABSTRACT

Apparatus for use in association with a mold used on a blow molding machine to produce a molded container with a bottom portion that includes a hollow expeller extending into the interior of the container. The apparatus includes an elongated forming rod. The forming rod is sectioned to separate with the mold halves and that functions to cut off the parison and form the bottom of the container. An actuator then causes the forming rod to force the bottom portion into the container inverting it and forming the expeller. The method of forming the container includes the timing of the inversion of the expeller to take place after the blowing,and release of blowing pressure, but prior to the firming of the molded material.

June 25, c PARKER METHOD AND APPARATUS FOR BLOW MOLDING AXIALLY DEFORMABLE CONTAINERS 2 Sheets-Sheet 1 Filed July 50, 1971 PARKER METHOD AND APPARATUS FOR BLOW MOLDING June 25, 1974 AXIALLY DEFORMABLE CONTAINERS 2 Sheets-Sheet 2 Filed July 50, 1971 IN vE/Vra/e. 0 604 Pozmse UnitedStates Patent O f Int. Cl. B29c 17/07 U.S.Cl. 264-.94 8 Claims ABSTRACT OF THE DISCLOSURE Apparatus for use in association with a mold used on a blow molding machine to produce a molded container with a bottom portion that includes a hollow expeller extending into the interior of 'the container. The apparatus'includes an elongated forming rod. The forming rod is sectioned to separate with the mold halves and that functions: to cutoff the 'parison and form the bottom of the container. An actuator then causes the forming rod to force the bottom portion into the container inverting it-and forming the expeller.

The method of forming the container includes the timing' of the invers'ion or, the expeller to take place after the blowing; and releaseof blowing pressure, but prior to the firming of th'ernolded'material.

CROSS REFERENCE TO RELATED I, APPLICATION application is a continuation-impart of my applicationSer. No. 832, 25 7,, filed June 11, 1969, now abandoned.

" BACKGROUN D=OF THE INVENTION Blow molded plastic containers, particularly bottles, haveubeen formed with wall configurations permitting some axial compressive deformation for the expulsion of the bottle contents Prior. art ,axially compressible containers, have in general, not been satisfactory because their design has notpermitted sufiicient compression to expel all of the containers contents. A container that is fullyeifective in axial compression is illustrated in applicants Pat. No. 2,899,110. This container is capable of substantially complete expulsion of its contents, when used in conjunction with the push-up or expeller there illustrated. Thefpush up is designed to be located in the bottom of the container and to move in close proximity to the inner diameter of the container to expel the contents progressively, eventually contacting the neck of the container to expel substantialy all of the contents. The pushupfis eifective for this purpose even where viscous materials are contained.

a While the proposed push-up. is an essential feature it has thus far been difficult or impossible to incorporate inproduction containers because of the complexity and expense of the forming process. For example, high pro duction containers of pla sti'c or other deformable material are fre ciuently'ma'de by blow-molding. The blow molding process forcesa pliable tube or parison to contact the mold wallsby introducing pressure to the interior of the parison. The limits of expansion of the pliable material, together-with the requirement that the container be removable from the mold after firming makes it difiicult to incorporate a recess within the interior of the container. In additiom-any Slowing of the machine cycle time to permit additional steps has an immediate effect on cost.

It has been suggested that the container could be formed with an extension andthe. extension inverted after the container is removed from the mold. However, this process does not produce containers of consistent quality since the. molded material has become too firm and therefore 3,819,789 Patented June 25, 1974 must be subjected to major stress to cause the inversion. This process results in weak and defective containers at a high cost.

Thus it would be desirable if a method and apparatus could be provided for producing a push-up or expeller without defects and without substantially increasing the cost over that for standard blow molded articles of comparable size.

SUMMARY OF THE INVENTION The invention provides a method and apparatus for molding an axially deformable container while forming and deflecting into the container an expeller prior to the removal of the container from the mold and without substantially increasing machine cycle time.

More specifically, the invention achieves the formation and positioning of an expeller in a bottle by a blow molding sequence whereby the body of the bottle and a hollow bottom extension are simultaneously blown, the blowing pressure is released and the extension is forced upwardly into the bottle prior to the firming of the molded material.

Structurally, this mode of operation is achieved by employment of a two piece mold including a cavity, to create apush-up extension beyond the container bottom. With the mold section closed, and utilizing an elongated vertically movable forming rod to engage and deflect a closed end of the extension upwardly into the bottle a distance, such that, when the latter is fully twist-compressed, the expeller may project into the neck of the bottle.

The invention has utility in the formation of expellers in any type of deformable, moldable, containers where this function is desired. In this manner, the invention may make available to all prior art, molded compressible containers, the benefits associated with the use of such an expeller. However, the invention has particular applicability to the formation of containers by blow molding that are axially deformable, such as the spiral walled container illustrated in applicants US. Pat. No. 2,899,110.

The structure peculiar to the apparatus of the invention may be incorporated with existing molding apparatus as an attachment to the mold, or may be an integral part of the mold design.

Further, details of the invention and the operation of an illustrative embodiment will be more fully understood from the following detailed description of the accompanying drawings:

BRIEF DESCRIPTION OF THE DRAWINGS An exemplary embodiment of the invention is described as forming a container such as that illustrated in FIGS. 4 and 5. The bottle to be formed has configuration of multiple hollow thin wall spirals 10 which are deflectable together by relatively twisting the top and bottom of the bottle so that it compresses axially to expel the contents. During the final stages of expulsion the push-up or expeller 11 forces substantially all of the contents from the container precluding wastage of contents of a viscous or creamy nature that would tend to remain in the central interior of the bottle.

In reference to FIGS. 1 to 3, the blow molding equipment is shown to comprise a pair of mold sections 12 and 13 the latter being stationarily carried by support 14 with section 12 mounted for lateral actuation by a power source such as pressurized fluid piston and cylinder unit 15. Guides 16 may be provided for support within the suitable bearings, not shown. As will be understood the mold section interiors have recesses at 17 and 18 in keeping with the FIG. 4 shape of the bottle, as well as lower cavitations 19 in conformity with the expeller to be blown. In accordance with customary practice the open mold receives a tubular parison 20 extending beyond the lower boundary of the mold which is blown by nozzle 21 inserted after the parison to the mold configuration appearing in FIG. 2.

Associated with the mold is the mechanism generally indicated at 22 for projecting the elongated forming rod structure 23 upwardly into the mold through its bottom groove 24. The rod structure 23 comprises a pair of separable forming rod portions 25 mounted for vertical movement by carriers 26 which travel on guide rods 27 depending from the bottom mold blocks 28, the forming rod portions, being directly connected to links 29 pivoted at 30 at the inside of back-up inserts 31.

In addition to being pivotally mounted, the forming rod portions 25 are spring loaded into engagement with the respective portions of the bottom mold grooves 24 spring means 25a mounted on carriers 26. This arrangement give them a floating action so that they track along mold portions 24, maintaining contact without binding. As the mold closes the forming rod portions, terminal ends, act to pinch together and close the lower end of the parison 20. Elevation and retraction of the forming rod portions 25 is achieved by piston 32 having a flanged head 33 and operable within cylinder 34 mounted by bracket 35 to the support 14. Retraction of the forming rod portions 25 from their upwardly projected position results from engagement of the piston flange 33 with angular brackets 36 depending from the carrier sections 26.

In the container forming sequence, the parison is placed between the mold sections which are then closed to cut off the parison and form the container with the bottom extension 11a which, as shown in FIG. 2, tapers towards its lower end. When the mold is closed the parison is blown to expand it into contact with the mold. After the blowing pressure is released and while the plastic remains deformable, the piston 32 is actuated to engage its head flange 33 against the undersides of the carriers 26 and elevate the forming rod portions to the FIG. 3 position in which the forming rod portions are shown to have engaged and pushed the projection 11a upwardly into the bottle to form the push up, expeller or upwardly extending protuberance 11 which, as shown in FIG. 3, tapers towards its uper end and does not conform in shape with the vertically extending walls of the rod portions 25. Thereupon the elevator piston returns to its starting position and the mold sections open to release the blow molded bottle, carrying with them and spreading apart the forming rod portions 25 shown in FIG. 1. The entire forming operation takes place within the normal complete cycle of the molding machine for a container with out a push-up, thereby conserving valuable machine time.

Having described my invention, I now claim:

1. Apparatus for molding containers comprising:

mold means for producing a container having an extension projecting below the bottom of said container;

said mold means comprising two separable sections;

forming rod means for pushing and inverting said extension into the interior of said container, said form- 4 ing rod means comprising separable-rod portions; each associated with a mold section, and being relatively movable laterally towards and other with said mold section's;

away from each a carrier means for each rod portion;

means connecting each rod portion to said carriermeans for lateral movement relative thereto;

common actuator means for moving 'saidcarrier means and the connected rod portions toward and aw from said mold means; I

a guideway on each mold section engaged by asso ciated rod portion; and biasing means acting on the rod portions for continli f ously urging each rod portion towards, its'ass'oeiated I guideway.

2. The apparatus of claim 1 wherein said biasin g'means comprises a spring acting between and 1ts connected rod portion.

3. The apparatus of claim I, wherein said adtuator each carrier means means and a carrier means have 'late'rally extending sti'rfaces engageable with each other after relative lateral motion for moving said carrier means towards and away from said mold sections. f

4. The apparatus ofclaim 1, wherein a gu'ide meaiis for a said carrier means extends downwardly from each" mold section.

from said mold sections.

6. The apparatus of claim 5, wherein? one of said mold sections is mountedon a'stationary support and the other of said mold sections is moved towards and away from said supportby an actuating device, and

said actuating means for moving the carrier means is mounted on said stationary sup'porn 7. The apparatus of claim '1 wherein:

said biasing means comprises a'spring a cting'between" 1 each carrier means and its connected rod portion,

wardly from each mold section,

a guide means for a said'ca'rrier means extends doWnsaid actuator means and a carrier means have laterally extending surfaces engageable with" each other after relative lateral motion for moving said carrier means towards and away from said mold sections,

one of said mold sections is mounted on a stationary support and the other of said mold sections is moved towards and away from said support by an actuating device, and

said actuating means for. moving the carrier means is mounted on said stationary support p I p 8. The method of blow molding an integralplastic container having a body portion, an open top portion and a closed bottom portion including a protuberance extend 1 ing upwardly into the interior of the container' and tap ing towards its upper end, comprisingthestps of:

placing a deformable plastic p aris'o' n betweenjfseparated mold sections configured to" form said portion, said top portion and downwardly extend-i, ing base portion tapering toward s its lowern epd; closing the mold sections to-cutqoff the parison ,at -the-;. top and bottom of the mold; p blowing the parison to expand it into contact .w'ithtthe 12;.

mold; I then releasing the blowing pressure; and 1 after the blowingpressurerisreleasedand while .tl1eplastic remains deformable raising core-rod means having a vertical sidewall to push said downwardly extending base portion into the body of the container.:- to form said upwardly extending protuberance tapering towards its upperend, the top of the core. rod means forming a bottomtpart of'rthe imoldythearelawvtionship of the upwardly extending protuberance and the core rod means being such that the upwardly extending protuberance lacks complete conformance to said core rod means.

References Cited 5 UNITED STATES PATENTS 8/1962 Clanton et a1. 425-121 X 1/1968 Hagen 425-216 5/1969 Carr 425-444 x 7/1935 Calderara 215-1 C UX l/1942 Sanders 215-1 C UK 6 2,899,110 8/1959 Parker 215-1 C UX 3,143,420 8/1964 Swanson et a1. 215-1 C UX FOREIGN PATENTS 911,228 11/1962 Great Britain 264-98 1,001,672 8/1965 Great Britain 264-98 220,099 11/ 1957 Australia 264-98 1,288,010 2/1962 France 264-98 JAN H. SILBAUGH, Primary Examiner U.S. Cl. X.R.

264-296; 425-387 B, 398, 457, Dig. 205, Dig. 214 

